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| - Heat transfer is always directed from a higher to a lower temperature. Denser <a href="http://en.wikipedia.org/wiki/Density">http://en.wikipedia.org/wiki/Density</a> substances are usually better conductors; metals are excellent conductors. The law of heat conduction also know as Fourier's law states that the time rate of heat flow Q through a slab (or a portion of a perfectly insulated wire, as shown in the figure) is proportional <a href="http://en.wikipedia.org/wiki/Proportionalto">http://en.wikipedia.org/wiki/Proportionalto</a> the gradient <a href="http://en.wikipedia.org/wiki/Gradientof">http://en.wikipedia.org/wiki/Gradientof</a> temperature difference:
- In heat transfer, conduction (or heat conduction) is the transfer of thermal energy between regions of matter due to a temperature gradient. Heat always flows from a region of higher temperature to a region of lower temperature, and results in the elimination of temperature differences by establishing thermal equilibrium. Conduction takes place in all forms of matter, viz. solids, liquids, gases and plasmas, but does not require any bulk motion of matter. In solids, it is due to the combination of vibrations of the molecules in a lattice or phonons with the energy transported by free electrons. In gases and liquids, conduction is due to the collisions and diffusion of the molecules during their random motion. In the engineering sciences, heat transfer includes the processes of thermal radi
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| abstract
| - In heat transfer, conduction (or heat conduction) is the transfer of thermal energy between regions of matter due to a temperature gradient. Heat always flows from a region of higher temperature to a region of lower temperature, and results in the elimination of temperature differences by establishing thermal equilibrium. Conduction takes place in all forms of matter, viz. solids, liquids, gases and plasmas, but does not require any bulk motion of matter. In solids, it is due to the combination of vibrations of the molecules in a lattice or phonons with the energy transported by free electrons. In gases and liquids, conduction is due to the collisions and diffusion of the molecules during their random motion. In the engineering sciences, heat transfer includes the processes of thermal radiation, convection, and sometimes mass transfer and often more than one of these processes occurs in a given situation.
- Heat transfer is always directed from a higher to a lower temperature. Denser <a href="http://en.wikipedia.org/wiki/Density">http://en.wikipedia.org/wiki/Density</a> substances are usually better conductors; metals are excellent conductors. The law of heat conduction also know as Fourier's law states that the time rate of heat flow Q through a slab (or a portion of a perfectly insulated wire, as shown in the figure) is proportional <a href="http://en.wikipedia.org/wiki/Proportionalto">http://en.wikipedia.org/wiki/Proportionalto</a> the gradient <a href="http://en.wikipedia.org/wiki/Gradientof">http://en.wikipedia.org/wiki/Gradientof</a> temperature difference: A is the transversal surface area, is the thickness of the body of matter through which the heat is passing, k is a conductivity constant dependent on the nature of the material and its temperature, and is the temperature difference through which the heat is being transferred. This law forms the basis for the derivation of the heat equation <a href="http://en.wikipedia.org/wiki/Heat_equation.">http://en.wikipedia.org/wiki/Heat_equation.</a> R-value <a href="http://en.wikipedia.org/wiki/R-valueis">http://en.wikipedia.org/wiki/R-valueis</a> the unit for heat resistance, the reciprocal of the conductance. Ohm's law is the electrical analogue of Fourier's law.
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